/*
 * Copyright (c) 2011, the Dart project authors.
 * 
 * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.dart.tools.ui.internal.text.html;

import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTError;
import org.eclipse.swt.graphics.FontData;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.swt.widgets.Display;

import java.io.IOException;
import java.io.Reader;
import java.net.URL;

/**
 * Provides a set of convenience methods for creating HTML pages.
 * <p>
 * Moved into this package from <code>org.eclipse.jface.internal.text.revisions</code>.
 * </p>
 */
public class HTMLPrinter {

  private static RGB BG_COLOR_RGB = null;

  static {
    final Display display = Display.getDefault();
    if (display != null && !display.isDisposed()) {
      try {
        display.asyncExec(new Runnable() {
          /*
           * @see java.lang.Runnable#run()
           */
          @Override
          public void run() {
            BG_COLOR_RGB = display.getSystemColor(SWT.COLOR_INFO_BACKGROUND).getRGB();
          }
        });
      } catch (SWTError err) {
        // see: https://bugs.eclipse.org/bugs/show_bug.cgi?id=45294
        if (err.code != SWT.ERROR_DEVICE_DISPOSED) {
          throw err;
        }
      }
    }
  }

  public static void addBullet(StringBuffer buffer, String bullet) {
    if (bullet != null) {
      buffer.append("<li>"); //$NON-NLS-1$
      buffer.append(bullet);
      buffer.append("</li>"); //$NON-NLS-1$
    }
  }

  public static void addPageEpilog(StringBuffer buffer) {
    buffer.append("</font></body></html>"); //$NON-NLS-1$
  }

  public static void addPageProlog(StringBuffer buffer) {
    insertPageProlog(buffer, buffer.length());
  }

  public static void addParagraph(StringBuffer buffer, Reader paragraphReader) {
    if (paragraphReader != null) {
      addParagraph(buffer, read(paragraphReader));
    }
  }

  public static void addParagraph(StringBuffer buffer, String paragraph) {
    if (paragraph != null) {
      buffer.append("<p>"); //$NON-NLS-1$
      buffer.append(paragraph);
    }
  }

  public static void addSmallHeader(StringBuffer buffer, String header) {
    if (header != null) {
      buffer.append("<h5>"); //$NON-NLS-1$
      buffer.append(header);
      buffer.append("</h5>"); //$NON-NLS-1$
    }
  }

  public static String convertToHTMLContent(String content) {
    content = replace(content, '&', "&amp;"); //$NON-NLS-1$
    content = replace(content, '"', "&quot;"); //$NON-NLS-1$
    content = replace(content, '<', "&lt;"); //$NON-NLS-1$
    return replace(content, '>', "&gt;"); //$NON-NLS-1$
  }

  /**
   * Replaces the following style attributes of the font definition of the <code>html</code>
   * element:
   * <ul>
   * <li>font-size</li>
   * <li>font-weight</li>
   * <li>font-style</li>
   * <li>font-family</li>
   * </ul>
   * The font's name is used as font family, a <code>sans-serif</code> default font family is
   * appended for the case that the given font name is not available.
   * <p>
   * If the listed font attributes are not contained in the passed style list, nothing happens.
   * </p>
   * 
   * @param styles CSS style definitions
   * @param fontData the font information to use
   * @return the modified style definitions
   */
  public static String convertTopLevelFont(String styles, FontData fontData) {
    boolean bold = (fontData.getStyle() & SWT.BOLD) != 0;
    boolean italic = (fontData.getStyle() & SWT.ITALIC) != 0;

    // See: https://bugs.eclipse.org/bugs/show_bug.cgi?id=155993
    String size = Integer.toString(fontData.getHeight())
        + ("carbon".equals(SWT.getPlatform()) ? "px" : "pt"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$

    String family = "'" + fontData.getName() + "',sans-serif"; //$NON-NLS-1$ //$NON-NLS-2$
    styles = styles.replaceFirst(
        "(html\\s*\\{.*(?:\\s|;)font-size:\\s*)\\d+pt(\\;?.*\\})", "$1" + size + "$2"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
    styles = styles.replaceFirst(
        "(html\\s*\\{.*(?:\\s|;)font-weight:\\s*)\\w+(\\;?.*\\})", "$1" + (bold ? "bold" : "normal") + "$2"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ //$NON-NLS-5$
    styles = styles.replaceFirst(
        "(html\\s*\\{.*(?:\\s|;)font-style:\\s*)\\w+(\\;?.*\\})", "$1" + (italic ? "italic" : "normal") + "$2"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ //$NON-NLS-5$
    styles = styles.replaceFirst(
        "(html\\s*\\{.*(?:\\s|;)font-family:\\s*).+?(;.*\\})", "$1" + family + "$2"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
    return styles;
  }

  public static void endBulletList(StringBuffer buffer) {
    buffer.append("</ul>"); //$NON-NLS-1$
  }

  public static void insertPageProlog(StringBuffer buffer, int position) {
    insertPageProlog(buffer, position, getBgColor());
  }

  public static void insertPageProlog(StringBuffer buffer, int position, RGB bgRGB) {
    if (bgRGB == null) {
      insertPageProlog(buffer, position);
    } else {
      StringBuffer pageProlog = new StringBuffer(60);
      pageProlog.append("<html><body text=\"#000000\" bgcolor=\""); //$NON-NLS-1$
      appendColor(pageProlog, bgRGB);
      pageProlog.append("\">"); //$NON-NLS-1$
      buffer.insert(position, pageProlog.toString());
    }
  }

  public static void insertPageProlog(StringBuffer buffer, int position, RGB bgRGB,
      String styleSheet) {

    if (bgRGB == null) {
      insertPageProlog(buffer, position, styleSheet);
    } else {
      StringBuffer pageProlog = new StringBuffer(300);

      pageProlog.append("<html>"); //$NON-NLS-1$

      appendStyleSheetURL(pageProlog, styleSheet);

      pageProlog.append("<body text=\"#000000\" bgcolor=\""); //$NON-NLS-1$
      appendColor(pageProlog, bgRGB);
      pageProlog.append("\">"); //$NON-NLS-1$

      buffer.insert(position, pageProlog.toString());
    }
  }

  public static void insertPageProlog(StringBuffer buffer, int position, RGB bgRGB,
      URL styleSheetURL) {

    if (bgRGB == null) {
      insertPageProlog(buffer, position, styleSheetURL);
    } else {
      StringBuffer pageProlog = new StringBuffer(300);

      pageProlog.append("<html>"); //$NON-NLS-1$

      appendStyleSheetURL(pageProlog, styleSheetURL);

      pageProlog.append("<body text=\"#000000\" bgcolor=\""); //$NON-NLS-1$
      appendColor(pageProlog, bgRGB);
      pageProlog.append("\">"); //$NON-NLS-1$

      buffer.insert(position, pageProlog.toString());
    }
  }

  public static void insertPageProlog(StringBuffer buffer, int position, String styleSheet) {
    insertPageProlog(buffer, position, getBgColor(), styleSheet);
  }

  public static void insertPageProlog(StringBuffer buffer, int position, URL styleSheetURL) {
    insertPageProlog(buffer, position, getBgColor(), styleSheetURL);
  }

  public static void insertStyles(StringBuffer buffer, String[] styles) {
    if (styles == null || styles.length == 0) {
      return;
    }

    StringBuffer styleBuf = new StringBuffer(10 * styles.length);
    for (int i = 0; styles != null && i < styles.length; i++) {
      styleBuf.append(" style=\""); //$NON-NLS-1$
      styleBuf.append(styles[i]);
      styleBuf.append('"');
    }

    // Find insertion index
    // a) within existing body tag with trailing space
    int index = buffer.indexOf("<body "); //$NON-NLS-1$
    if (index != -1) {
      buffer.insert(index + 5, styleBuf);
      return;
    }

    // b) within existing body tag without attributes
    index = buffer.indexOf("<body>"); //$NON-NLS-1$
    if (index != -1) {
      buffer.insert(index + 5, ' ');
      buffer.insert(index + 6, styleBuf);
      return;
    }
  }

  public static String read(Reader rd) {

    StringBuffer buffer = new StringBuffer();
    char[] readBuffer = new char[2048];

    try {
      int n = rd.read(readBuffer);
      while (n > 0) {
        buffer.append(readBuffer, 0, n);
        n = rd.read(readBuffer);
      }
      return buffer.toString();
    } catch (IOException x) {
    }

    return null;
  }

  public static void startBulletList(StringBuffer buffer) {
    buffer.append("<ul>"); //$NON-NLS-1$
  }

  private static void appendColor(StringBuffer buffer, RGB rgb) {
    buffer.append('#');
    buffer.append(Integer.toHexString(rgb.red));
    buffer.append(Integer.toHexString(rgb.green));
    buffer.append(Integer.toHexString(rgb.blue));
  }

  private static void appendStyleSheetURL(StringBuffer buffer, String styleSheet) {
    if (styleSheet == null) {
      return;
    }

    buffer.append("<head><style CHARSET=\"ISO-8859-1\" TYPE=\"text/css\">"); //$NON-NLS-1$
    buffer.append(styleSheet);
    buffer.append("</style></head>"); //$NON-NLS-1$
  }

  private static void appendStyleSheetURL(StringBuffer buffer, URL styleSheetURL) {
    if (styleSheetURL == null) {
      return;
    }

    buffer.append("<head>"); //$NON-NLS-1$

    buffer.append("<LINK REL=\"stylesheet\" HREF= \""); //$NON-NLS-1$
    buffer.append(styleSheetURL);
    buffer.append("\" CHARSET=\"ISO-8859-1\" TYPE=\"text/css\">"); //$NON-NLS-1$

    buffer.append("</head>"); //$NON-NLS-1$
  }

  private static RGB getBgColor() {
    if (BG_COLOR_RGB != null) {
      return BG_COLOR_RGB;
    }
    return new RGB(255, 255, 225); // RGB value of info bg color on WindowsXP

  }

  private static String replace(String text, char c, String s) {

    int previous = 0;
    int current = text.indexOf(c, previous);

    if (current == -1) {
      return text;
    }

    StringBuffer buffer = new StringBuffer();
    while (current > -1) {
      buffer.append(text.substring(previous, current));
      buffer.append(s);
      previous = current + 1;
      current = text.indexOf(c, previous);
    }
    buffer.append(text.substring(previous));

    return buffer.toString();
  }

  private HTMLPrinter() {
  }
}
